The objective of this proposal is to study the mechanisms involved in the biogenesis of translatable mRNA from its high molecular weight precursor, HnRNA. HnRNA from adenovirus-infected HeLa cell nuclei will be used to translate the mRNA sequences present in it in a cell system from Ehrlich ascites tumor cells. Investigations will be conducted in the following areas: i) mechanism of translation and identification of the products; ii) structural modifications of HnRNA to generate translatable mRNA during processing; and iii) protein factors involved in the processing of HnRNA. This research will elucidate some of the specific control mechanisms and steps of gene expression during replication of normal and virus-infected eukaryotic cells.